mfd: stmfx: Disable IRQ in suspend to avoid spurious interrupt

mfd: stmfx: Disable IRQ in suspend to avoid spurious interrupt

[ Upstream commit 97eda5dcc2cde5dcc778bef7a9344db3b6bf8ef5 ]

When STMFX supply is stopped, spurious interrupt can occur. To avoid that,
disable the interrupt in suspend before disabling the regulator and
re-enable it at the end of resume.

Fixes: 06252ade9156 ("mfd: Add ST Multi-Function eXpander (STMFX) core driver")
Signed-off-by: Amelie Delaunay <amelie.delaunay@st.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>